In U.S. Pat. No. 4,456,882 I disclose a technique for NMR Sample Spinning using cylindrical, ceramic sample containers with press-fit plastic turbines on hydrostatic air bearings. A co-pending application, Ser. No. 07/607,521, discloses novel radial inflow microturbines and other improvements appropriate for high temperature applications. Another co-pending application, Ser. No. PCT/US91/01225 discloses an NMR Sample spinner capable to achieving supersonic surface speeds. Other NMR MAS spinners are disclosed in U.S. Pat. Nos. 4,254,373, 4,275,350, 4,511,841, 4,899,111 and the references cited therein.
It is well known that considerable sample heating, sometimes in excess of 90.degree. C., results from frictional heating of the bearing gas in high-speed NMR sample spinners.
Cooling by insentropic expansion in turbines is well known and widely used in Brayton cycle refrigeration systems.